Printing ink



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COATING ORfiASliC Patentecfoct. 1942 UNITED STATES bi use more: UHMJPATENT OFFICE PRINTING INK No Drawing. Application June 4, 1942, SerialNo. 445,803

2 Claims.

This invention relates to improvements in printing inks.

This application is a continuation in part of our application Serial No.396,294, filed June 2', 1941, for Printing ink.

This invention relates to printing inks and particularly to those inwhich a binder is employed with a solvent to form a varnish in which apigment is incorporated. The binder is soluble in the solvent and in thesolvent with 'a limited quantity of Water but is not soluble in thesolvent with an unlimited quantity of water. Such inks are particularlydesirable because they have high water tolerance because the binder issoluble in the solvent and a limited quantity of water and willtherefore not set up on a printing press, even when high humidities areencountered. These inks may, however, after printing be treated withwater, for example in the form of steam or a fine spray so that thebinder at the surface of a printed film will separate from the solventbecause of the presence of more than a limited quantity of water in thesolvent and will thus form a thin hard film of the binder over theprinted film to thereby prevent offset. Such inks are useful also incases where it is not desired to use the water to prevent offset.

The objects of this invention are:

First, to provide a new and improved printing ink.

Second, the provide such a printing ink having a high melting pointbinder with a hard surface and gloss.

Third, to provide such a printing ink which has water tolerance and willnot set up on the press in the presence of high atmospheric humidities.

Fourth, to provide such an ink which can be treated with water afterprinting to prevent offset and which will set up very quickly when it isso treated.

Fifth, to provide such an ink in which phenolic resins are incorporatedwith a liquid polyglycol as a solvent.

Further objects and advantages pertaining to details and economies willappear from the description to follow.

In our improved printing ink, we use a liquid polyglycol such asdiethylene glycol as the solvent for the varnish. We prefer to use 50%of the weight of the varnish of this liquid polyglycol.

With the liquid polyglycol, we incorporate a anhydrous condition by theapplication of heat,

resin of the phenolic type which consists of a phenol formaldehydecondensation product which has been modified with rosin. The rosinmodification must be such as to make the resin soluble in ethyl alcohol,and in the liquid polyglycol used as a solvent in the varnish. The resinhas a high acid number of or more. It is a solid resin. We prefer to use10% of the weight of the varnish of this phenolic resin.

With this phenolic resin, we employ either a resin comprising rosinmodified with an alpha beta unsaturated organic polybasic acid such asmaleic or fumaric or a terpene hydrocarbon of the formula Ciel-I16modified with an alpha beta unsaturated organic polybasic acid such asmaleic and fumaric or a combination of said resins. These resins whichare, employed are solid and are soluble in the liquid polyglycol such asdiethylene glycol. We prefer to use 40% by weight of the varnish of suchresins or a mixture thereof. The terpene hydrocarbons which are suitablewhen modified as above described are alpha terpinene, beta terpinene,pinene, alpha pinene, beta pinene, dipentene, limonene, or terpinolene.We have found that the phenolic resin above described is not soluble incold diethylene glycol and if it is put into temporary solution in an itwill separate on standing from the diethylene glycol or other liquidpolyglycol. Such a solution has practically no water tolerance and theresin will immediately separate from any temporary solution if thetemporary solution is exposed to normal humidity such as would beencountered in printing establishments.

We have found, however, that if such a phenolic resin is employed incombination with either the resin comprising rosin modified with analpha beta unsaturated organic polybasic acid or terpene hydrocarbon ofthe formula ClOHlG modified with an alpha beta unsaturated organicpolybasic acid or a mixture of these resins, the ink will have watertolerance and will not set up on a press even when high humidityconditions are encountered in a printing establishment. The link is thususable because it does not set up on the press and when it is treatedwith steam or water after printing, the film of binder will form overthe surface of the printed film and thus prevent offset.

The ink has a hard surface and a gloss and it also has the property ofsetting up very quickly after it has been printed and when it is treatedwith Water either by subjecting the printed film, for example, to steamor to a water spray.

Search Ream The pigment employed may be selected from standard pigments.We prefer to use pigments insoluble in the pclyglycol solvent and inwater.

The terms and expressions which have been herein employed are used asterms of description and not of limitation and there is no intention inthe use of such terms and expressions of excluding any equivalents ofthe features shown and described, or portions thereof. It is recognizedthat various modifications are possible within the scope of theinvention claimed.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

l. A printing ink comprising a varnish stable against separation of thebinder at high atmospheric humidity conditions comprising a solventcomprising a liquid polyglycol, a binder comprising a solid resinselected from the group con.- sisting of rosin modified by an alpha betaunsaturated organic polybasic acid and a terpene hydrocarbon of theformula ClOHlfi modified by an alpha beta unsaturated organic polybasicacid, mixed with a solid alcohol soluble phenolic resin soluble in saidsolvent and comprising a phenol formaldehyde condensation productmodified with rosin, and a pigment.

2. A printing ink comprising a varnish stable against separation of thebinder at high atmospheric humidity conditions comprising a solventcomprising 50 parts by weight of a liquid polyglycol, a bindercomprising parts by weight of a solid resin selected from the groupconsisting of rosin modified by an alpha beta unsaturated organicpolybasic acid and a terpene hydrocarbon of the formula C10H16 modifiedby an alpha beta unsaturated organic polybasic acid, mixed with 10 partsby weight of a solid alcohol soluble phenolic resin soluble in saidsolvent and comprising a phenolformaldehyde condensation productmodified with rosin, and a pigment.

DONALD ROBERT ERICKSON. PAUL J. THOMA.

